Liquid crystal display devices are display devices that utilize a liquid crystal composition for display. The typical display mode thereof is applying voltage to a liquid crystal composition sealed between paired substrates to change the alignment state of liquid crystal molecules in the liquid crystal composition according to the applied voltage, thereby controlling the amount of light transmitted. These liquid crystal display devices, having characteristics such as thin profile, light weight, and low power consumption, have been used in a broad range of fields.
The display modes of liquid crystal display devices include horizontal alignment modes, which control the alignment of liquid crystal molecules by rotating them mainly in a plane parallel to the substrate surfaces. The horizontal alignment modes have received attention because these modes make it easy to achieve wide viewing angle characteristics. For example, the in-plane switching (IPS) mode and the fringe field switching (FFS) mode, both a type of horizontal alignment mode, are widely used in recent liquid crystal display devices for smartphones or tablet PCs.
There is continuing research and development of the horizontal alignment modes to achieve higher definition pixels, an improved transmittance, and an improved response speed to improve display quality. Patent Literature 1 discloses a technique to improve the response speed, for example. Specifically, Patent Literature 1 relates to an IPS mode liquid crystal display device, and discloses a technique in which a liquid crystal composition containing a photopolymerizable monomer is placed between paired substrates and the photopolymerizable monomer is polymerized to form a polymer structure to connect the paired substrates. The literature teaches that this technique allows the liquid crystal display device to exhibit excellent responsivity in a wide temperature range. Patent Literature 2 relates to a FFS mode liquid crystal display device and discloses a technique in which openings having, for example, a rectangular or substantially rhombic shape are formed in the common electrode, and liquid crystal molecules facing each other in the width direction of each opening are rotated in opposite directions. The literature teaches that this technique contributes to a higher response speed.